1. Field of the Invention
The present invention relates to an optical imaging device, and more particularly, to an optical imaging device with a plurality of reflective optical units for capturing image simultaneously by a single image capturing module.
2. Description of the Prior Art
In the modern consumer electronic products market, a portable electronic product such as a personal digital assistant, a smart phone or a mobile phone is equipped with a touch control device as an interface for data transmission. Since consumer electronic products have become lighter, thinner, shorter, and smaller, there is no space on these products for containing a conventional input device, such as a mouse, a keyboard and so on. Furthermore, with development of tablet computers focusing on humanity design, a display with the touch control device has gradually become one of the key components in various electronic products. However, as technology advances, a variety of touch control technologies such as a resistive type, a capacitive type, an ultrasonic type, an infrared type, an optical masking type, an optical imaging type and so on have been developing. Since technology level and cost diverge, the above-mentioned touch control technologies have been implemented in various fields. For example, principle of the optical imaging design is to utilize two image capturing modules located at two corners of the display for detecting a location of an object on the display. Then, the location of the object on the display is calculated by coordinate transformation. Thus, compared with the conventional resistive type or capacitive type touch device, it not only has advantages of high accuracy, good stability, low damage rate and being capable of multi-touch, but also has advantage of low cost. Especially, the optical imaging design is overwhelmingly advantageous in the large-size display market. However, the conventional optical imaging device not only requires more than two image capturing modules so as to detect a shadow formed by the object, but also has an issue of synchronization of capturing images by the two image capturing modules. Consequently, it results in enhancement of cost. In order to solve above drawbacks, Taiwan Patent No. M338402 discloses a display with reflective mirrors disposed on a bottom-left and a bottom-right corners within a touch control area, so as to reflect the image of the object to a single image sensor. However, when the display is in large size, it needs the image sensor with a larger sensing area and will cause an issue of image deformation. For solving the above drawbacks, the image capturing module needs to calibrate the deformed image in particular. Furthermore, since the disposal positions of the reflective mirrors are within the touch control area, it is not convenient for a user to use the computer. As a result, design of an optical imaging device for reducing cost and being capable of solving the problem of synchronization of capturing images is an important issue of the touch technique.